Again... who says anyone is fixing anything? They've got a new material. Do you know the cost? Because it could be cheaper. It's very simple... when upgrades present themselves, and margins remain the same, you'd be stupid not to take them. And like with the Gorilla Glass, since Corning is updating their entire production lines for their new glasses, it's an at-par upgrade for them to purchase, and likely more expensive to stand still.
And yes, "some" did not. A small fraction of the whole. Just like I should be able to buy a gallon of milk that has a sell-by date 2 weeks out and not have it spoil before then... "some" don't make it that far before going bad. Or, in the electronics world, I should be able to buy a TV and have it last longer than the year warranty... "some" don't make it that far... hence, the warranty guaranteeing me it does.